FLUORINATED FULLERENES - SYNTHESIS AND CHARACTERIZATION

The existence of the fully fluorinated fullerene, C60F60, is still sub ject to controversy. Mass spectrometric evidence shows that it exists, albeit in trace amounts five orders of magnitude in concentration bel ow the most abundant C60F40-42. Generally, mixtures of C60Fn are obtai ned where n ranges from 30 to 52, depending on fluorinating conditions . The species with n = 36 is particularly stable. Attempts to increase n by use of the strongly fluorinating halogen fluorides, ClF3 or BrF5 , have led to products C60FxXyOz (X = Br or Cl), where the origin of t he oxygen is probably hydrolysis during analysis. Fluorinated C60 crys tallizes as a mixture of hexagonal close packed (40%) and face-centere d cubic (60%) phases. X-ray analysis yields an average C-F bond length of 1.49 angstrom. Fluorination of C70 leads to mixtures with maximum average stoichiometries of C70F52.